Many different applications exist for three-dimensional imaging. While many current image-viewing media, such as display screens and photographs, display only in two dimensions, the information from the third dimension may still be useful, even in such two-dimensional displays.
For example, teleconferencing may be used to allow several geographically separate participants to be brought into a single virtual environment. Three dimensional information may be used in such teleconferencing, to provide realism and an ability to modify the displayed information, to accommodate facial movement.
Facial orientation and expression may be used to drive models over the network to produce and enhance the realism.
Three-dimensional information may also be usable over a network, using, for example, the concept of cyber touch. Those people browsing the web page of a certain server such as a museum may be allowed to touch certain objects using a haptic device. One such device is available at http://digimuse.usc.edu/IAM.htm.
Work along this line has been carried out under the names aerial triangulation, and binocular stereo.
Three-dimensional models may be obtained using a laser scanner. Other techniques are also known for obtaining the three-dimensional models. Practical limitations, however, such as cost, complexity, and delays may hamper obtaining an accurate three-dimensional model.
If two cameras are completely calibrated, then obtaining a full 3D model from 2D information is known. See the book “Multiple View Geometry in Computer Vision”, Richard Hartley and Andrew Zisserman, Cambridge University Press, June 2000. Calibration of cameras includes internal calibration and external calibration. Internal calibration refers to the characteristic parameters of the camera such as focal length, optical center, distortion, skew, . . . External parameters which describe the relative position and orientation of the cameras with respect to each other. It is known to go to 3D from a disparity map if cameras are both internally and externally calibrated.
Internal calibration of cameras is a well understood problem in the literature, with packages freely available to perform this step. Intel's OpenCV Library at http://www.intel.com/research/mrl/research/opencv/, for example, can be used. These techniques such as these may be used to internally calibrate the cameras offline. However, the present system does not require calibration.